Semiconductor light emitting device including substrate having protection layers and method for manufacturing the same

ABSTRACT

The present invention provides a compound semiconductor light emitting device including: an Si—Al substrate; protection layers formed on top and bottom surfaces of the Si—Al substrate; and a p-type semiconductor layer, an active layer, and an n-type semiconductor layer which are sequentially stacked on the protection layer formed on the top surface of the Si—Al substrate, and a method for manufacturing the same.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Korean Patent Application No.10-2008-0109792 and 10-2009-0016947 filed with the Korea IntellectualProperty Office on Nov. 6, 2008 and Feb. 27, 2009, the disclosure ofwhich are incorporated herein by references.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a compound semiconductor light emittingdevice and a method for manufacturing the same; and, more particularly,to a compound semiconductor light emitting device including a protectionlayer on the surface of a Si—Al substrate, and a method formanufacturing the same.

2. Description of the Related Art

A GaN-based semiconductor, which is expressed asAl_(x)Ga_(y)In_((1-x-y))N(0≦x≦1, 0≦y≦1, 0≦x+y≦1), has been used for ablue or green LED(Light Emitting Diode) as a compound semiconductorappropriate for light emission in blue and ultraviolet regions. Agenerally used GaN-based LED includes an n-type GaN-based semiconductorlayer, an active layer, a p-type GaN-based semiconductor layer and twoelectrodes(n-side electrode and p-side electrode) which are sequentiallygrown on a sapphire substrate. Since the sapphire substrate used as agrowth substrate is made of insulating material, the two electrodes arehorizontally arranged.

Since in the GaN-based LED having such a horizontal structure, both ofthe two electrodes are positioned at an upper part of the LED, the LEDshould have a wide area. In addition, a transparent electrode forcurrent spreading and the n-side electrode are disposed close to eachother, which makes the LED vulnerable to defect caused by staticelectricity.

Instead of the GaN-based LED with the horizontal structure having thedisadvantage, a vertical GaN-based LED is recently used which uses aconductive SiC substrate as a growth substrate of a GaN-basedsemiconductor. However, this has a disadvantage in that the high-costSiC substrate is used.

Another vertical GaN-based LED is manufactured through a bonding processof a conductive substrate and a separation process of a sapphiresubstrate. For example, Korean Patent Laid-open Publication No.10-2004-0058479 discloses a vertical GaN-based LED including aconductive substrate such as an Si substrate bonded to a GaN-basedsemiconductor layer by a conductive adhesion layer.

However, in the case of the conventional vertical GaN-based LEDmanufactured through the bonding process of the conductive substratesuch as the Si substrate and the separation process of the sapphiresubstrate, there is caused a defect such as a crack in the GaN-basedsemiconductor layer when separating the sapphire substrate through laserirradiation. This is because CTE(Coefficient of ThermalExpansion)(approximately 2.6 ppm/K) of Si that is material of theconductive substrate is much lower than CTE(6 to 7 ppm/K) of thesapphire substrate.

More specifically, if the conductive substrate made of Si is bonded tothe GaN-based semiconductor layer at a temperature of approximately 200to 400° C. and then cooled at a room temperature, the conductivesubstrate contracts slightly, while the sapphire substrate contractsconsiderably. As a result, a large tensile stress is applied to thesapphire substrate to thereby warp the conductive substrate and thesapphire substrate. If the sapphire substrate is separated through laserirradiation in a warped state due to the tensile stress, mechanicalimpact is applied to an interface between the sapphire substrate and theGaN-based semiconductor layer to thereby cause a lot of cracks in theGaN-based semiconductor layer.

Therefore, an Si—Al substrate having a similar CTE to that of thesapphire substrate is recently used instead of the Si substrate as theconductive substrate, thereby obtaining a high-quality verticalsemiconductor light emitting device which reduces the generation ofcrack.

However, in the case when the Si—Al substrate is used, Al of the Si—Alsubstrate is easily etched due to attack of chemicals such as acid andalkali used in a process of manufacturing a light emitting device tothereby generate severe unevenness on the surface of the Si—Alsubstrate, which causes an error that the GaN-based semiconductor layeris peeling off which is bonded to the Si—Al substrate.

SUMMARY OF THE INVENTION

The present invention has been proposed in order to overcome theabove-described problems and it is, therefore, an object of the presentinvention to provide a compound semiconductor light emitting devicecapable of preventing Al of an Si—Al substrate from being etched due tochemicals by additionally forming a protection layer on the surface ofthe Si—Al substrate to prevent the attack of chemicals such as acid andalkali, and a method for manufacturing the same.

Further, another object of the present invention is to provide acompound semiconductor light emitting device capable of improvingsurface roughness of an Si—Al substrate, and a method for manufacturingthe same.

In accordance with one aspect of the present invention to achieve theobject, there is provided a compound semiconductor light emitting deviceincluding: an Si—Al substrate; protection layers formed on top andbottom surfaces of the Si—Al substrate; and a p-type semiconductorlayer, an active layer, and an n-type semiconductor layer which aresequentially stacked on the protection layer formed on the top surfaceof the Si—Al substrate.

Herein, the protection layer may be formed of metal or conductivedielectric.

Further, the metal may be formed of any one selected from a groupconsisting of Ni, Au, Cu, W, Cr, Mo, Pt, Ru, Rh, Ti, and Ta, or an alloyof two or more selected from the group.

Further, the conductive dielectric may be formed of any one selectedfrom a group consisting of ITO(Indium Tin Oxide), IZO(Indium ZincOxide), and CIO(Copper Indium Oxide).

Further, the protection layer may be formed at a thickness of 0.01 μm ormore and 20 μm or less.

Further, the compound semiconductor light emitting device includes abonding metal layer formed between the protection layer formed on thetop surface of the Si—Al substrate and the p-type semiconductor layer.

Further, the compound semiconductor light emitting device includes areflective metal layer formed between the bonding metal layer and thep-type semiconductor layer.

In accordance with another aspect of the present invention to achievethe object, there is provided a method for manufacturing a compoundsemiconductor light emitting device including the steps of: sequentiallyforming an n-type semiconductor layer, an active layer, and a p-typesemiconductor layer on a growth substrate; preparing an Si—Al substrateformed including a protection layer on the surface; bonding the Si—Alsubstrate including the protection layer on the surface to the p-typesemiconductor layer; separating the growth substrate from the n-typesemiconductor layer; forming a plurality of n-side electrodes on then-type semiconductor layer; and dicing the n-type semiconductor layer,the active layer, the p-type semiconductor layer, the protection layer,and the Si—Al substrate between the n-side electrodes to be divided intochip units.

Further, the protection layer may be formed by using metal or conductivedielectric in the step of preparing the Si—Al substrate including theprotection layer on the surface.

Further, in the case when the protection layer is formed of the metal,the metal may be formed by any one of electroless plating, metaldeposition, sputtering and CVD(Chemical Vapor Deposition).

Further, in the case when the protection layer is formed of theconductive dielectric, the conductive dielectric may be formed bydeposition or sputtering.

Further, the protection layer may be formed on the surface of the Si—Alsubstrate at a thickness of 0.01 μm or more and 20 μm or less.

Further, the method includes a step of: performing CMP(ChemicalMechanical Polishing) on the surface of the protection layer after thestep of preparing the Si—Al substrate including the protection layer onthe surface.

Further, the step of bonding the Si—Al substrate including theprotection layer on the surface may be performed by directly bonding theSi—Al substrate including the protection layer on the surface to thep-type semiconductor layer.

Further, the step of bonding the Si—Al substrate including theprotection layer on the surface may be performed by bonding the Si—Alsubstrate including the protection layer on the surface to the p-typesemiconductor layer by using a bonding metal layer.

Further, the method includes a step of: forming a reflective metal layeron the p-type semiconductor layer after the step of forming the p-typesemiconductor layer.

In accordance with still another aspect of the present invention toachieve the object, there is provided a compound semiconductor lightemitting device including: an Si—Al substrate; a protection layer formedon a top surface of the Si—Al substrate to expose a portion of the Si—Alsubstrate; a conductive layer formed on the top surface of the Si—Alsubstrate including the protection layer; a p-type semiconductor layer,an active layer, and an n-type semiconductor layer which aresequentially stacked on the conductive layer; and a contact metal layerformed on a bottom surface of the Si—Al substrate.

Herein, the protection layer may be formed of an insulator.

In accordance with still another aspect of the present invention toachieve the object, there is provided a method for manufacturing acompound semiconductor light emitting device including the steps of:sequentially forming an n-type semiconductor layer, an active layer, anda p-type semiconductor layer on a growth substrate; preparing an Si—Alsubstrate including a protection layer on the other portions except forsome portions of a top surface; forming a conductive layer on the topsurface of the Si—Al substrate including the protection layer; bondingthe conductive layer formed on the top surface of the Si—Al substrate tothe p-type semiconductor layer; separating the growth substrate from then-type semiconductor layer; forming a plurality of n-side electrodes onthe n-type semiconductor layer; lapping a bottom surface of the Si—Alsubstrate including the protection layer; forming a contact metal layeron the bottom surface of the Si—Al substrate; and dicing the n-typesemiconductor layer, the active layer, the p-type semiconductor layer,the conductive layer, the protection layer, the Si—Al substrate, and thecontact metal layer between the n-side electrodes to be divided intochip units.

Herein, the step of preparing the Si—Al substrate including theprotection layer on the other portions except for the some portions ofthe top surface includes steps of: forming the protection layer on theentire surface of the Si—Al substrate; and exposing the some portions ofthe top surface of the Si—Al substrate by removing a portion of theprotection layer.

Further, the protection layer may be formed by using an insulator in thestep of forming the protection layer on the entire surface of the Si—Alsubstrate.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects and advantages of the present generalinventive concept will become apparent and more readily appreciated fromthe following description of the embodiments, taken in conjunction withthe accompanying drawings of which:

FIG. 1 is a cross-sectional view showing a structure of a compoundsemiconductor light emitting device in accordance with a firstembodiment of the present invention;

FIGS. 2 to 9 are cross-sectional views sequentially illustratingprocesses of a method for manufacturing a compound semiconductor lightemitting device in accordance with the first embodiment of the presentinvention;

FIG. 10 is a cross-sectional view showing a structure of a compoundsemiconductor light emitting device in accordance with a secondembodiment of the present invention; and

FIGS. 11 to 19 are cross-sectional views sequentially illustratingprocesses of a method for manufacturing a compound semiconductor lightemitting device in accordance with the second embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE PREFERABLE EMBODIMENTS

Embodiments of a compound semiconductor light emitting device and amethod for manufacturing the same in accordance with the presentinvention will be described in detail with reference to the accompanyingdrawings. When describing them with reference to the drawings, the sameor corresponding component is represented by the same reference numeraland repeated description thereof will be omitted.

First Embodiment Structure of a Compound Semiconductor Light EmittingDevice in Accordance with a First Embodiment

A compound semiconductor light emitting device in accordance with afirst embodiment of the present invention will be described in detailwith reference to FIG. 1.

FIG. 1 is a cross-sectional view showing a structure of a compoundsemiconductor light emitting device in accordance with the firstembodiment of the present invention.

As shown in FIG. 1, the compound semiconductor light emitting device 100in accordance with the first embodiment of the present inventionincludes a substrate formed of an alloy of Si and Al(hereinafterreferred to as ‘Si—Al substrate’) 101 and protective layers 120 formedon a top surface and a bottom surface of the Si—Al substrate 101.

On the protective layer 120 formed on the top surface of the Si—Alsubstrate 101, there are sequentially stacked a bonding metal layer 102,a reflective metal layer 103, a p-type semiconductor layer 104, anactive layer 105, and an n-type semiconductor layer 106.

The p-type and n-type semiconductor layers 104 and 106 and the activelayer 105 may be formed of a GaN-based semiconductor, i.e.Al_(x)Ga_(y)In_((1-x-y))N(0≦x≦1, 0≦y≦1, 0≦x+y≦1) semiconductor material,or the like, and constitute a light emitting structure. An n-sideelectrode 107 is formed on the n-type semiconductor layer 106.

The reflective metal layer 103 interposed between the bonding metallayer 102 and the p-type semiconductor layer 104 reflects light impingedfrom the semiconductor layer upward to thereby further increasebrightness of the compound semiconductor light emitting device 100.

The reflective metal layer 103 may be formed of metal with highreflectivity, e.g., metal selected from a group consisting of Au, Ag,Al, Rh, and an alloy of two or more among them. However, the reflectivemetal layer 103 may not be formed if necessary.

The bonding metal layer 102 bonds the Si—Al substrate 101 to the lightemitting structure. As for the bonding metal layer 102, Au or the likemay be used.

Herein, although the compound semiconductor light emitting device 100 ofthe first embodiment of the present invention includes the bonding metallayer 102, the Si—Al substrate 101 may be directly bonded to the p-typesemiconductor layer 104 without the bonding metal layer 102.

Further, the compound semiconductor light emitting device 100 inaccordance with the first embodiment of the present invention uses theSi—Al substrate 101 as a conductive substrate as mentioned above. TheSi—Al substrate has advantages in terms of CTE(Coefficient of ThermalExpansion), thermal conductivity, mechanical processing, and cost.

In other words, the CTE of the Si—Al substrate 101 is similar tothat(approximately 6 to 7 ppm/K) of the sapphire substrate(see ‘150’ ofFIG. 2). Therefore, in the case when the compound semiconductor lightemitting device 100 is manufactured by using the Si—Al substrate 101, itis possible to remarkably reduce warpage of the substrate and cracks ofthe light emitting structure which are caused during the bonding processof the conventional conductive substrate formed of Si and during theseparation process of the sapphire substrate through laser irradiation,thereby obtaining the high-quality compound semiconductor light emittingdevice 100 which reduces the defects.

In addition, since the Si—Al substrate 101 has the thermal conductivityof approximately 120 to 180 W/m·K, it has an excellent heat dischargecharacteristic. Moreover, since the Si—Al substrate 101 can be easilymanufactured by melting Si and Al at high pressure, it is possible toeasily obtain the Si—Al substrate 101 at a low cost.

Particularly, in the compound semiconductor light emitting device 100 inaccordance with the first embodiment of the present invention, theprotection layers 120 are additionally formed on the top and bottomsurfaces of the Si—Al substrate 101 to prevent chemical attack on theSi—Al substrate 101.

Herein, the protection layers 120 may be formed of metal, conductivedielectric, or the like. At this time, in the case when the protectionlayers 120 are formed of metal, the metal may be formed of any oneselected from a group consisting of Ni, Au, Cu, W, Cr, Mo, Pt, Ru, Rh,Ti, and Ta, or an alloy of two or more selected from the group.

Further, in the case when the protection layers 120 are formed ofconductive dielectric, the conductive dielectric may be formed ofITO(Indium Tin Oxide), IZO(Indium Zinc Oxide), CIO(Copper Indium Oxide),or the like.

In case when the protection layers 120 are formed of metal, theprotection layers may be formed by an electroless plating method. Atthis time, seed metal layers 110 may be further formed between the Si—Alsubstrate 101 and the protection layers 120 formed of metal to play arole of seeds in a plating process of the protection layers 120. Theseed metal layers 110 may be formed of Ti/Au or the like.

Herein, the protection layers 120 formed of the metal may be formed by amethod such as metal deposition, sputtering, or CVD(Chemical VaporDeposition) other than the electroless plating method as describedabove.

Further, in the case when the protection layers 120 are formed of theconductive dielectric, the protection layers 120 formed of theconductive dielectric may be formed by a method such as deposition orsputtering.

It is preferable that the protection layers 120 are formed atthicknesses of 0.01 μm or more and 20 μm or less and more preferably,they are formed at thicknesses of 1 μm or more and 10 μm or less.

Method for Manufacturing a Compound Semiconductor Light Emitting Devicein Accordance with the First Embodiment

Hereinafter, a method for manufacturing a compound semiconductor lightemitting device in accordance with the first embodiment of the presentinvention will be described in detail with reference to FIGS. 2 to 9.

FIGS. 2 to 9 are cross-sectional views sequentially illustratingprocesses of a method for manufacturing a compound semiconductor lightemitting device in accordance with the first embodiment of the presentinvention.

First, as shown in FIG. 2, after preparing a sapphire substrate 150 as agrowth substrate, as shown in FIG. 3, an n-type semiconductor layer 106,an active layer 105, and a p-type semiconductor layer 104 aresequentially formed on the sapphire substrate 150.

Thereafter, as shown in FIG. 4, a reflective metal layer 103 is formedon the p-type semiconductor layer 104 by using metal material with highreflectivity, e.g., Au, Al, Ag, or Rh. Herein, the reflective metallayer 103 may not be formed if necessary.

Thereafter, as shown in FIG. 5, a protection layer 120 is formed on thesurface of an Si—Al substrate 101. The protection layer 120 may beformed by using metal or conductive dielectric.

Herein, in the case when the protection layer 120 is formed of metal,the protection layer 120 may be formed of any one selected from a groupconsisting of Ni, Au, Cu, W, Cr, Mo, Pt, Ru, Rh, Ti, and Ta, or an alloyof two or more selected from the group by a method such as electrolessplating, metal deposition, sputtering, or CVD(Chemical VaporDeposition).

At this time, in the case when the protection layer 120 formed of themetal is formed by the electroless plating, a seed metal layer 110 maybe additionally formed to play a role of a seed in a plating process ofthe protection layer 120 before forming the protection layer 120 on thesurface of the Si—Al substrate 101.

Further, in the case when the protection layer 120 is formed of theconductive dielectric, the protection layer 120 may be formed ofITO(Indium Tin Oxide), IZO(Indium Zinc Oxide), CIO(Copper Indium Oxide),or the like by a method such as deposition or sputtering.

It is preferable that the protection layer 120 is formed on the entiresurface of the Si—Al substrate 101 at a thickness of 0.01 μm or more and20 μm or less and more preferably, it is formed at a thickness of 1 μmor more and 10 μm or less.

In the case when the protection layer 120 is formed at a thickness below0.01 μm, the protection layer 120 can not satisfactorily suppress theattack of chemicals such as HCl, HF and KOH which are described belowand in the case when it is formed at a thickness above 20 μm, CTE of theSi—Al substrate 101 may change. Therefore, it is preferable that theprotection layer 120 is formed at the thickness within theabove-mentioned range.

At this time, although not shown in the drawings, after forming theprotection layer 120, surface roughness can be improved by performingCMP(Chemical Mechanical Polishing) on the surface of the protectionlayer 120.

As described above, after preparing the Si—Al substrate 101 having theprotection layer 120 on the surface, as shown in FIG. 6, the Si—Alsubstrate 101 having the protection layer 120 on the surface is bondedto the reflective metal layer 103 by using a bonding metal layer 102.

Herein, although the Si—Al substrate 101 is bonded by using the bondingmetal layer 102 as described above, the Si—Al substrate 101 having theprotection layer 120 on the surface may be directly bonded to thereflective metal layer 103 without the bonding metal layer 102.

Thereafter, as shown in FIG. 7, the sapphire substrate 150 is separatedfrom the n-type semiconductor layer 106 through an LLO(Laser Lift Off)process. After separating the sapphire substrate 150, a cleaning processmay be performed using chemicals such as HCl, HF, and KOH.

Thereafter, as shown in FIG. 8, a plurality of n-side electrodes 107 areformed on the n-type semiconductor layer 106 which is exposed byseparating the sapphire substrate 150.

Herein, before forming the n-side electrodes 107, a texturing processusing KOH or the like may be performed on the surface of the n-typesemiconductor layer 106 in order to enhance light extraction efficiencyof the device.

Thereafter, as shown in FIG. 9, the n-type semiconductor layer 106, theactive layer 105, the p-type semiconductor layer 104, the reflectivemetal layer 103, the bonding metal layer 102, the protection layer 120,the seed metal layer 110 and the Si—Al substrate 101 between the n-sideelectrodes 107 are diced to be divided into chip units. Consequently, itis possible to obtain the compound semiconductor light emitting device100 in accordance with the first embodiment of the present invention.

As described above, in accordance with the first embodiment of thepresent invention, it is possible to prevent Al of the Si—Al substrate101 from being etched due to the chemicals used in the cleaning processperformed after separating the sapphire substrate 150, e.g., HCl, HF andKOH, or KOH used in the texturing process of the surface of the n-typesemiconductor layer 106 by additionally forming the protection layer 120such as Ni on the surface of the Si—Al substrate 101. Therefore, inaccordance with the first embodiment of the present invention, it ispossible to prevent unevenness from being formed on the surface of theSi—Al substrate 101, thereby preventing the light emitting structurebonded to the Si—Al substrate 101 from peeling off.

Further, in the case when using metal such as Ni for the protectionlayer 120, surface roughness of the Si—Al substrate 101 can be improvedto thereby firmly bond the Si—Al substrate 101 and the light emittingstructure.

That is, according to the related art, as the Si—Al substrate 101 passesthrough a cleaning process using chemicals such as acid to remove anative oxide film before forming the bonding metal layer 102, the Al ofthe surface of the Si—Al substrate 101 is etched and surface unevennessof average 200 to 500 nm is formed at the same time, while, inaccordance with the first embodiment of the present invention, if NiCMP(Chemical Mechanical Polishing) is performed after forming the metalsuch as Ni as the protection layer 120 on the surface of the Si—Alsubstrate 101, the surface unevenness is reduced below 5 nm, therebyimproving the surface roughness like a mirror surface.

Therefore, since the surface roughness of the Si—Al substrate 101 can beimproved, it is possible to firmly bond the Si—Al substrate and thelight emitting structure and enhance bonding yield.

Second Embodiment Structure of a Compound Semiconductor Light EmittingDevice in Accordance with a Second Embodiment

A compound semiconductor light emitting device in accordance with asecond embodiment of the present invention will be described in detailwith reference to FIG. 10. The same configuration of the secondembodiment as that of the first embodiment will be omitted and onlydifferent configuration of the second embodiment will be described indetail.

FIG. 10 is a cross-sectional view showing a structure of a compoundsemiconductor light emitting device in accordance with a secondembodiment of the present invention.

As shown in FIG. 10, the compound semiconductor light emitting device100 in accordance with the second embodiment of the present inventionincludes most of the same components as those of the compoundsemiconductor light emitting device of the first embodiment, only it isdifferent from the compound semiconductor light emitting device of thefirst embodiment in that a protection layer 120 is not formed on bothtop and bottom surfaces of the Si—Al substrate 101 but on the topsurface of the Si—Al substrate 101 to expose a portion of the Si—Alsubstrate 101, a conductive layer 122 is additionally formed on theprotection layer 120 and the top surface of the Si—Al substrate 101exposed by the protection layer 120, and a contact metal layer 123 isformed on the bottom surface of the Si—Al substrate 101.

Particularly, in the compound semiconductor light emitting device inaccordance with the second embodiment of the present invention, it ispreferable that the protection layer 120 is formed of an insulatorinstead of metal or conductive dielectric.

That is, in the compound semiconductor light emitting device inaccordance with the second embodiment of the present invention, theprotection layer 120 is formed of the insulator instead of metal orconductive dielectric, while the protection layer 120 is formed toexpose a portion of the top surface of the Si—Al substrate 101 and theconductive layer 122 is additionally formed on the top surface of theSi—Al substrate including the protection layer 120 for conductionbetween the Si—Al substrate 101 including the protection layer 120 and alight emitting structure positioned at an upper part of the protectionlayer 120.

Herein, the conductive layer 122 may be formed of metal or the like.

Method for Manufacturing a Compound Semiconductor Light Emitting Devicein Accordance with the Second Embodiment

Hereinafter, a method for manufacturing a semiconductor light emittingdevice in accordance with the second embodiment of the present inventionwill be described in detail. The same configuration of the secondembodiment as that of the first embodiment will be omitted and onlydifferent configuration of the second embodiment will be described indetail.

First, as shown in FIGS. 2 to 4, an n-type semiconductor layer 106, anactive layer 105, a p-type semiconductor layer 104, and a reflectivemetal layer 103 are formed on a sapphire substrate 150 in order. Herein,the reflective metal layer 103 may not be formed if necessary.

Thereafter, as shown in FIG. 11, a protection layer 120 is formed on theentire surface of an Si—Al substrate 101.

Herein, the protection layer 120 may be formed of an insulator. Theprotection layer 120 formed of the insulator may be formed at athickness of 0.01 μm or more and 1 μm or less by a method such asCVD(Chemical Vapor Deposition) or coating.

At this time, although not shown in the drawings, after forming theprotection layer 120, CMP(Chemical Mechanical Polishing) may beperformed on the surface of the protection layer 120.

Thereafter, as shown in FIG. 12, a portion of the protection layer 120is removed by a method such as etching to expose a portion of a topsurface of the Si—Al substrate 101.

Thereafter, as shown in FIG. 13, a conductive layer 122 is formed on thetop surface of the Si—Al substrate 101 including the protection layer120.

Thereafter, as shown in FIG. 14, the conductive layer 122 formed on thetop surface of the Si—Al substrate 101 is bonded to the reflective metallayer 103 by using a bonding metal layer 102.

Thereafter, as shown in FIG. 15, the sapphire substrate 150 is separatedfrom the n-type semiconductor layer 106 through an LLO(Laser Lift Off)process.

Herein, after separating the sapphire substrate 150, a cleaning processmay be performed using chemicals such as HCl, HF, and KOH. At this time,in accordance with the second embodiment of the present invention, sincethe protection layer 120 and the conductive layer 120 are formed on thesurface of the Si—Al substrate 101, it is possible to prevent Al of theSi—Al substrate 101 from being etched due to the chemicals used in thecleaning process.

Thereafter, as shown in FIG. 16, a plurality of n-side electrodes 107are formed on the n-type semiconductor layer 106 which is exposed byseparating the sapphire substrate 150.

Herein, before forming the n-side electrodes 107, a texturing processusing KOH or the like may be performed on the surface of the n-typesemiconductor layer 106 in order to enhance light extraction efficiencyof the device. At this time, in accordance with the present embodiment,since the protection layer 120 and the conductive layer 122 are formedon the surface of the Si—Al substrate 101, it is possible to prevent Alof the Si—Al substrate 101 from being etched due to the chemicals usedin the texturing process.

Thereafter, as shown in FIG. 17, a bottom surface of the Si—Al substrate101 including the protection layer 120 is removed at a predeterminedthickness by performing a lapping process.

Thereafter, as shown in FIG. 18, a contact metal layer 123 is formed onthe bottom surface of the Si—Al substrate 101 exposed through thelapping process.

Thereafter, as shown in FIG. 19, the n-type semiconductor layer 106, theactive layer 105, the p-type semiconductor layer 104, the reflectivemetal layer 103, the bonding metal layer 102, the conductive layer 122,the protection layer 120, the Si—Al substrate 101, and the contact metallayer 123 between the n-side electrodes 107 are diced to be divided intochip units. Consequently, it is possible to obtain the compoundsemiconductor light emitting device 100 in accordance with the secondembodiment of the present invention.

The method for manufacturing the compound semiconductor light emittingdevice in accordance with the second embodiment of the present inventioncan obtain the same operation and effect as those of the firstembodiment.

As described above, the compound semiconductor light emitting device andthe method for manufacturing the same in accordance with the presentinvention can prevent Al of the Si—Al substrate from being etched due tothe chemicals by additionally forming the protection layer on thesurface of the Si—Al substrate to prevent the attack of chemicals suchas acid and alkali. Therefore, it is possible to prevent the unevennessfrom being formed on the surface of the Si—Al substrate to therebyprevent the light emitting structure bonded to the Si—Al substrate frompeeling off.

Further, in the case when using the metal for the protection layerformed on the surface of the Si—Al substrate, the surface roughness canbe improved through the protection layer formed of metal. Therefore, itis possible to firmly bond the Si—Al substrate and the light emittingstructure and enhance the bonding yield.

As described above, although the preferable embodiments of the presentinvention have been shown and described, it will be appreciated by thoseskilled in the art that substitutions, modifications and variations maybe made in these embodiments without departing from the principles andspirit of the general inventive concept, the scope of which is definedin the appended claims and their equivalents.

1-21. (canceled)
 22. A compound semiconductor light emitting devicecomprising; an Si—Al substrate; a protection layer formed on a topsurface of the Si—Al substrate to expose a portion of the Si—Alsubstrate; a conductive layer formed on the top surface of the Si—Alsubstrate including the protection layer; a p-type semiconductor layer,an active layer, and an n-type semiconductor layer which aresequentially stacked on the conductive layer; and a contact metal layerformed on a bottom surface of the Si—Al substrate.
 23. The compoundsemiconductor light emitting device of claim 22, wherein the protectionlayer is formed of an insulator.
 24. A method for manufacturing acompound semiconductor light emitting device comprising the steps of:sequentially forming an n-type semiconductor layer, an active layer, anda p-type semiconductor layer on a growth substrate; preparing an Si—Alsubstrate formed including a protection layer on the surface; bondingthe Si—Al substrate including the protection layer on the surface to thep-type semiconductor layer; separating the growth substrate from then-type semiconductor layer; forming a plurality of n-side electrodes onthe n-type semiconductor layer; and dicing the n-type semiconductorlayer, the active layer, the p-type semiconductor layer, the protectionlayer, and the Si—Al substrate between the n-side electrodes to bedivided into chip units.
 25. The method of claim 24, wherein theprotection layer is formed by using metal or conductive dielectric inthe step of preparing the Si—Al substrate including the protection layeron the surface.
 26. The method of claim 25, wherein in the case when theprotection layer is formed of the metal, the metal is formed by any oneof electroless plating, metal deposition, sputtering and CVD (ChemicalVapor Deposition).
 27. The method of claim 25, wherein in the case whenthe protection layer is formed of the conductive dielectric, theconductive dielectric is formed by deposition or sputtering.
 28. Themethod of claim 24, wherein the protection layer is formed on thesurface of the Si—Al substrate at a thickness of 0.01 μm or more and 20μm or less.
 29. The method of claim 24, further comprising a step of:performing CMP (Chemical Mechanical Polishing) on the surface of theprotection layer after the step of preparing the Si—Al substrateincluding the protection layer on the surface.
 30. The method of claim24, wherein the step of bonding the Si—Al substrate including theprotection layer on the surface is performed by directly bonding theSi—Al substrate including the protection layer on the surface to thep-type semiconductor layer.
 31. The method of claim 24, wherein the stepof bonding the Si—Al substrate including the protection layer on thesurface is performed by bonding the Si—Al substrate including theprotection layer on the surface to the p-type semiconductor layer byusing a bonding metal layer.
 32. The method of claim 24, furthercomprising a step of: forming a reflective metal layer on the p-typesemiconductor layer after the step of forming the p-type semiconductorlayer.
 33. A method for manufacturing a compound semiconductor lightemitting device comprising the steps of: sequentially forming an n-typesemiconductor layer, an active layer, and a p-type semiconductor layeron a growth substrate; preparing an Si—Al substrate including aprotection layer on the other portions except for a portion of a topsurface; forming a conductive layer on the top surface of the Si—Alsubstrate including the protection layer; bonding the conductive layerformed on the top surface of the Si—Al substrate to the p-typesemiconductor layer; separating the growth substrate from the n-typesemiconductor layer; forming a plurality of n-side electrodes on then-type semiconductor layer; lapping a bottom surface of the Si—Alsubstrate including the protection layer; forming a contact metal layeron the bottom surface of the Si—Al substrate; and dicing the n-typesemiconductor layer, the active layer, the p-type semiconductor layer,the conductive layer, the protection layer, the Si—Al substrate, and thecontact metal layer between the n-side electrodes to be divided intochip units.
 34. The method of claim 33, wherein the step of preparingthe Si—Al substrate including the protection layer on the other portionsexcept for the some portions of the top surface includes steps of:forming the protection layer on the entire surface of the Si—Alsubstrate; and exposing the some portions of the top surface of theSi—Al substrate by removing a portion of the protection layer.
 35. Themethod of claim 34, wherein the protection layer is formed by using aninsulator in the step of forming the protection layer on the entiresurface of the Si—Al substrate.